Plasma-Assisted ALD of Al2O3 at Low Temperatures: Reaction Mechanisms and Material Properties

Langereis, E Erik; Bouman, Menno; Keijmel, J Jeroen; Heil, Sbs Stephan; Sanden, van de Mcm Richard; Kessels, Wmm Erwin

doi:10.1149/1.2980000

Cited by 19 publications

(16 citation statements)

References 14 publications

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“…ERD measurement showed a decrease in hydrogen content by increasing the number of PRs. Larger contents of carbon and hydrogen in the film obtained with 1 PR suggest that CH x and OH species are present in the layer …”

Section: Resultsmentioning

confidence: 95%

TiO₂ thin film patterns prepared by chemical vapor deposition and atomic layer deposition using an atmospheric pressure microplasma printer

Aghaee

Verheyen

Stevens³

et al. 2019

Plasma Processes & Polymers

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A microplasma printer is employed to deposit thin film patterns of TiO2 by titanium tetra‐isopropoxide and N2/O2 plasma at atmospheric pressure. The setup is adopted to carry out deposition in two configurations, namely under chemical vapor deposition (CVD) and atomic layer deposition (ALD) modes. The properties of TiO2, as well as the patterning resolution, are investigated. The amorphous TiO2 deposited in the CVD mode contains a relatively high level of impurities (residual carbon content of 5–10 at.%) and is characterized by a low refractive index of 1.8. With the ALD mode on the other hand, TiO2 is obtained with a low level of impurities (<1 at.% C and <2 at.% N), a refractive index of 1.98, and a growth per cycle of 0.15 nm. Furthermore, the spatial resolution for a 8‐nm‐thick film is determined by X‐ray photoelectron spectroscopy line scan and found to be equal to 2,000 and 900 µm for the CVD and ALD modes, respectively. This study can be regarded as the first step toward area‐selective CVD and ALD of TiO2 by a microplasma printer, which can be further explored and extended to other material systems.

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Section: Resultsmentioning

confidence: 95%

TiO₂ thin film patterns prepared by chemical vapor deposition and atomic layer deposition using an atmospheric pressure microplasma printer

Aghaee

Verheyen

Stevens³

et al. 2019

Plasma Processes & Polymers

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“…24 A trace of unreacted TMA can also be seen in the figure. 24,27 Both the second and the third TMA exposure show less CH 4 production and the signature of (unreacted) TMA becomes more evident. During the H 2 O half-cycle shown in Fig.…”

Section: Growth Mechanism Of Ald Of Al 2 Omentioning

confidence: 99%

Revisiting the growth mechanism of atomic layer deposition of Al2O3: A vibrational sum-frequency generation study

Vandalon

Kessels

2017

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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The growth mechanism of the prototypical atomic layer deposition (ALD) process of Al2O3 using Al(CH3)3 (TMA) and H2O has been revisited on the basis of insights obtained with the nonlinear optical analysis technique of broadband sum-frequency generation (BB-SFG). With BB-SFG spectroscopy, both the –CH3 and –OH surface groups ruling the growth of Al2O3 by ALD were detected and could be monitored during the ALD process with submonolayer sensitivity. Several remaining questions pertaining to the growth mechanism of Al2O3 were addressed. The reaction kinetics of the H2O half-cycle were studied for ALD between 100 and 300 °C, and the reaction cross section σ was determined. The cross section at 300 °C was fairly large (σ = 3 × 10−19 cm2) and it decreased with decreasing temperature. Below 200 °C, the cross section also clearly varied with the surface coverage. For example, at 100 °C, the cross section started at σ = 1 × 10−20 cm2 for a full –CH3 coverage and decreased to σ = 3 × 10−21 cm2 for a 60% coverage. This coverage dependence of the reaction kinetics also explains the presence of the persistent –CH3 groups at low temperatures which are no longer reactive toward H2O. By a dedicated study using x-ray photo-emission spectroscopy, it was demonstrated that the persistent –CH3 groups were not incorporated into the film as a contaminant species. The absolute –CH3 coverage was measured for ALD between 100 and 450 °C. With this data, steric hindrance was ruled out as the cause of the self-limiting behavior in the TMA half-cycle on basis of the decrease observed in the –CH3 coverage with temperature. The self-limiting behavior was attributed to the depletion of under coordinated O during the TMA half-cycle. Moreover, the chemisorption of TMA on the -OH surface groups during the TMA half-cycle was investigated. On average, 1.5 –CH3 ligands remained on the surface per deposited Al atom after the TMA half-cycle at 300 °C, and this number decreased to 0.8 at 100 °C. These insights into the underlying growth mechanism augment the understanding of Al2O3 ALD and reveal several nuances in this well-studied ALD process.

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“…In the early stage, the deposition of metal oxide, such as Al2O3 from trimethylaluminum and O3/H2O as the co-reactant, has been studied theoretically. [25][26][27][28][29] The surface hydroxyl groups are formed and their surface coverages affect the growth rate. For the deposition of metals, Elliott has proposed a mechanism for deposition of noble metals including Pd, Ir and Pt using homoleptic precursors and oxygen from DFT calculations.…”

Section: Introductionmentioning

confidence: 99%

Reaction Mechanism of the Metal Precursor Pulse in Plasma-Enhanced Atomic Layer Deposition of Cobalt and the Role of Surface Facets

Liu

Zhang

et al. 2020

J. Phys. Chem. C

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Cobalt is a potential candidate in replacing copper for interconnects and has been applied in the trenches and vias in semiconductor industry. A non-oxidizing reactant is required in plasmaenhanced atomic layer deposition (PE-ALD) of thin films of metals to avoid O-contamination. PE-ALD of Co has been demonstrated experimentally, but the growth mechanism and key reactions are not clear. In this paper, the reaction mechanism of metal cyclopentadienyl (Cp, C5H5) precursors (CoCp2) and NHx-terminated Co surface is studied by density functional theory (DFT) calculations. The Cp ligands are eliminated by CpH formation via a hydrogen transfer step and desorb from metal surface. The surface facet plays an important role in the reaction energies and activation barriers. The results show that on the NHx-terminated surfaces corresponding to ALD operating condition (temperature range 550K to 650K), the two Cp ligands are eliminated completely on Co(100) surface during the metal precursor pulse, resulting in Co atom deposited on the Co(100) surface. But the second Cp ligand reaction of hydrogen transfer is thermodynamically unfavourable on the Co(001) surface, resulting in CoCp fragment termination on Co(001) surface. The final terminations after metal precursor pulse are 3.03 CoCp/nm 2 on NHxterminated Co(001) surface and 3.33 Co/nm 2 on NHx-terminated Co(100) surface. These final structures after metal precursor pulse are essential to model the reaction during the following Nplasma step.

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Plasma-Assisted ALD of Al2O3 at Low Temperatures: Reaction Mechanisms and Material Properties

Cited by 19 publications

References 14 publications

TiO₂ thin film patterns prepared by chemical vapor deposition and atomic layer deposition using an atmospheric pressure microplasma printer

TiO₂ thin film patterns prepared by chemical vapor deposition and atomic layer deposition using an atmospheric pressure microplasma printer

Revisiting the growth mechanism of atomic layer deposition of Al2O3: A vibrational sum-frequency generation study

Reaction Mechanism of the Metal Precursor Pulse in Plasma-Enhanced Atomic Layer Deposition of Cobalt and the Role of Surface Facets

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Plasma-Assisted ALD of Al2O3 at Low Temperatures: Reaction Mechanisms and Material Properties

Cited by 19 publications

References 14 publications

TiO2 thin film patterns prepared by chemical vapor deposition and atomic layer deposition using an atmospheric pressure microplasma printer

TiO2 thin film patterns prepared by chemical vapor deposition and atomic layer deposition using an atmospheric pressure microplasma printer

Revisiting the growth mechanism of atomic layer deposition of Al2O3: A vibrational sum-frequency generation study

Reaction Mechanism of the Metal Precursor Pulse in Plasma-Enhanced Atomic Layer Deposition of Cobalt and the Role of Surface Facets

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Product

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TiO₂ thin film patterns prepared by chemical vapor deposition and atomic layer deposition using an atmospheric pressure microplasma printer

TiO₂ thin film patterns prepared by chemical vapor deposition and atomic layer deposition using an atmospheric pressure microplasma printer